Single-screw compressors including compression mechanisms for compressing refrigerant by rotations of screw rotors have been known in the art.
In a single-screw compressor (hereinafter referred to simply as a screw compressor) described in Japanese Patent Publication No. 2004-137934, for example, a screw rotor is housed in a cylinder, and a gate rotor is engaged with this screw rotor. In this manner, in helical grooves formed in the outer periphery of the screw rotor, a compression chamber is defined to be surrounded by a gate of the gate rotor, the screw rotor, and the inner wall of the cylinder. In the screw compressor, a suction port is formed at an end (a suction side) along the axis of the screw rotor, and a discharge port is formed at the other end (a discharge side) along the axis of the screw rotor.
During operation of the single-screw compressor, a fluid flows into the helical grooves through the suction port. In the helical grooves, a compression chamber is defined with rotation of the screw rotor. When the screw rotor in this state further rotates, the volume of the compression chamber enclosing the fluid gradually decreases. Accordingly, the fluid in the compression chamber is gradually compressed. Then, when the screw rotor in this state further rotates, the compression chamber and the discharge port communicate with each other. Consequently, the high-pressure fluid in the compression chamber is discharged to a predetermined space through the discharge port.